UV Light and Polymers
Ultraviolet (UV) light is a type of electromagnetic radiation – like radio waves, x-ray, and gamma rays – but is not visible to the human eye. UV light comes from the sun and is what gives us our tans – and sunburns – in the summer. UV light is high energy light, and too much exposure to it can damage human tissue as well as non-biological materials.
The long-chain polymer molecules of plastics can absorb the high energy from UV light. This absorbed energy is strong enough to break chemical bonds leading to a breakdown in material integrity. The result is a negative impact upon the material’s mechanical properties such as impact resistance and strength. The slow reduction in mechanical properties brought on by continued UV exposure is known as UV degradation. Because different chemical bonds within the polymer structure absorb different UV energies, the composition of the particular polymer material determines how it is affected by UV light. The UV behavior of polymer plastics has particular implications for plastics that will be exposed to sunlight such as outdoors or in an aerospace setting.
Effects of Degradation
Visible effects of UV degradation include a powdery or chalky residue on the surface of the plastic and a change in color. The surface may also brittle with evidence of cracking. Sticky residues may also be evident with chemicals appearing to seep or leak from the surface. These effects are predominantly the result of chemical reactions in the surface layer of the material and are unlikely to extend to depths below 0.5 mm.
Some plastics have been exposed to much higher UV radiation levels than on earth. Plastic components in the Hubble Space Telescope (HST) and the International Space Station (ISS) require materials that can withstand the UV exposure of outer space. Fluoropolymers such as FEP and polyimides like Kapton are plastics that have been successfully used for the HST and ISS.
UV degradation is thus an important consideration when choosing the best polymer material for your application. UV exposure also factors heavily into the lifespan of the material dependent upon its intended working environment.
UV Light and Zeus
Zeus polymer products show excellent weathering and are extremely resistant to prolonged exposure to UV light from sunlight. Fluoropolymers are particularly well-suited to these settings with no risk of component failure from UV exposure.
In other cases, it is also highly desirable that the polymer plastic be able to transmit or allow the passage of UV through. UV transmission can be affected by the crystallinity of the polymer structure as well as tubing wall thickness. UV transmission, for example, is a necessary quality for products such as plexiglass windows. For tubing applications, UV transmission is particularly useful for areas that require the tubing contents to be UV sterilized within the tubing.
For questions about UV light or other tubing applications that you may be considering, contact us or call: 1-800-526-3842 toll-free in the US or +1-803-268-9500 internationally today.